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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21fb175866805bcb9a45f5eef036bcb9feeed81220338663f6be3f34d442198c' 
  AND token = 'Z6UxqAVZuJ+5owC2QTrd2I6Wl6ZMBSraff5ldyyT5yg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}